1. Field of the Invention
The present invention relates to a transmitting apparatus and method, a receiving apparatus and method, and a providing medium. More particularly, the present invention relates to a transmitting apparatus and method, a receiving apparatus and method, and a providing medium which are suitably used, for example, in the case of encoding and transmitting time-series digital signals such as audio signals, and receiving and decoding the digital signals to reproduce them in real time on the receiving side.
2. Description of the Related Art
For example, when digital signals such as digital audio signals are transmitted from the transmitting side to the receiving side via a network, e.g., Internet, it is customary that the digital signals are transmitted after being compressed and encoded into coded data on the transmitting side, and the coded data is decoded on the receiving side, because the data rate of the digital signals is higher than the transmission band (i.e., the transmission rate) of the network. Such transmission and reception of digital signals is performed on the premise that the receiving side includes a decoder corresponding to an encoder provided on the transmitting side.
Coded data resulted from encoding made by an encoder on the transmitting side is transmitted to the receiving side via a network as mentioned above, but the transmission rate of the coded data in the network generally varies due to the amount of traffic, etc. Apart from the case where the coded data is all downloaded and then decoded on the receiving side, therefore, it may occur in the case of decoding the coded data while receiving the same that the transmission of the coded data becomes too late to decode and reproduce the audio signals in real time if the transmission rate of the network lowers below the data rate of the coded data.
Also, although a system of Internet or any other network is designed so as to avoid the transmission of the coded data from becoming too late as far as possible, it is nevertheless sometimes difficult to decode and reproduce audio signals in real time due to, e.g., the ability of hardware and the decoding method of a decoder on the receiving side.
More specifically, for example, when the coding method of an encoder on the transmitting side is complex, the decoding method of a decoder for decoding the coded data, which has been encoded by the encoder, is also usually complex. In such a case, if hardware on the receiving side has not a processing ability capable of coping with the complex decoding method, decoding of audio signals would be too late for the start of reproduction thereof. Further, the processing time required for the decoder to decode the coded data is greatly affected by the processing ability of hardware on the receiving side. Accordingly, if the processing ability of hardware on the receiving side is lower than expected by the transmitting side, the time taken for decoding the coded data would be longer than expected by the transmitting side, thus resulting in a difficulty in decoding and reproducing the audio signals in real time.
The present invention has been made in view of the state of art set forth above, and intends to decode and reproduce digital signals in real time.
According to a first aspect of the present invention, in a transmitting apparatus for outputting coded data resulted from encoding a time-series digital signal, the transmitting apparatus comprises a plurality of coding means for encoding the digital signal with a plurality of coding methods and outputting the coded data, instructing means for instructing, from among the plurality of coding methods, one for encoding a part or the whole of the digital signal, selecting means for selecting the coded data obtained with the coding method instructed from the instructing means, adding means for adding, to the coded data selected by the selecting means, coding method information indicating the coding method used for obtaining the selected coded data, and outputting means for outputting the selected coded data added with the coding method information.
According to a second aspect of the present invention, in a transmitting method for use in a transmitting apparatus for outputting coded data resulted from encoding a time-series digital signal, the transmitting apparatus comprises a plurality of coding means for encoding the digital signal with a plurality of coding methods and outputting the coded data, and the transmitting method comprises an instructing step of instructing, from among the plurality of coding methods, one for encoding a part or the whole of the digital signal, a selecting step of selecting the coded data obtained with the coding method instructed in the instructing step, an adding step of adding, to the coded data selected in the selecting step, coding method information indicating the coding method used for obtaining the selected coded data, and an outputting step of outputting the selected coded data added with the coding method information.
According to a third aspect of the present invention, in a providing medium for providing a computer program for rendering a computer to execute processing to output coded data resulted from encoding a time-series digital signal, the computer comprises a plurality of coding means for encoding the digital signal with a plurality of coding methods and outputting the coded data, and the computer program includes an instructing step of instructing, from among the plurality of coding methods, one for encoding a part or the whole of the digital signal, a selecting step of selecting the coded data obtained with the coding method instructed in the instructing step, an adding step of adding, to the coded data selected in the selecting step, coding method information indicating the coding method used for obtaining the selected coded data, and an outputting step of outputting the selected coded data added with the coding method information.
According to a fourth aspect of the present invention, in a receiving apparatus for receiving and processing coded data resulted from encoding a part or the whole of a time-series digital signal with one of a plurality of coding methods, the receiving apparatus comprises extracting means for extracting coding method information added to the coded data and indicating the coding method used for obtaining the coded data, recognizing means for recognizing a decoding method for decoding the coded data based on the coding method information, and decoding means for decoding the coded data with the decoding method recognized by the recognizing means.
According to a fifth aspect of the present invention, in a receiving method for receiving and processing coded data resulted from encoding a part or the whole of a time-series digital signal with one of a plurality of coding methods, the receiving method comprises an extracting step of extracting coding method information added to the coded data and indicating the coding method used for obtaining the coded data, a recognizing step of recognizing a decoding method for decoding the coded data based on the coding method information, and a decoding step for decoding the coded data with the decoding method recognized in the recognizing step.
According to a sixth aspect of the present invention, in a providing medium for providing a computer program for rendering a computer to process coded data resulted from encoding a part or the whole of a time-series digital signal with one of a plurality of coding methods, the computer program includes an extracting step of extracting coding method information added to the coded data and indicating the coding method used for obtaining the coded data, a recognizing step of recognizing a decoding method for decoding the coded data based on the coding method information, and a decoding step for decoding the coded data with the decoding method recognized in the recognizing step.
According to a seventh aspect of the present invention, in a providing medium for providing coded data resulted from encoding a time-series digital signal, the providing medium provides coded data and coding method information that are obtained by instructing, from among a plurality of coding methods, one for encoding a part or the whole of the digital signal, selecting the coded data resulted from encoding the digital signal with the instructed coding method, and adding, to the selected coded data, coding method information indicating the coding method used for obtaining the selected coded data.
According to an eighth aspect of the present invention, in a transmitting apparatus for transmitting coded data resulted from encoding a digital signal via a predetermined transmission line, the transmitting apparatus comprises a plurality of coding means for encoding the digital signal with a plurality of coding methods and outputting the coded data, detecting means for detecting a transmission rate of the transmission line, selecting means for selecting one of the plurality of coding methods which is able to provide coded data having a bit rate corresponding to the transmission rate of the transmission line, and transmitting means for transmitting the coded data obtained with the coding method selected by selecting means.
According to a ninth aspect of the present invention, in a transmitting method for use in a transmitting apparatus for transmitting coded data resulted from encoding a digital signal via a predetermined transmission line, the transmitting apparatus comprises a plurality of coding means for encoding the digital signal with a plurality of coding methods and outputting the coded data, and the transmitting method comprises a detecting step of detecting a transmission rate of the transmission line, a selecting step of selecting one of the plurality of coding methods which is able to provide coded data having a bit rate corresponding to the transmission rate of the transmission line, and a transmitting step of transmitting the coded data obtained with the coding method selected in the selecting step.
According to a tenth aspect of the present invention, in a providing medium for providing a computer program for rendering a computer to execute processing to transmit coded data resulted from encoding a digital signal via a predetermined transmission line, the computer comprises a plurality of coding means for encoding the digital signal with a plurality of coding methods and outputting the coded data, and the computer program includes a detecting step of detecting a transmission rate of the transmission line, a selecting step of selecting one of the plurality of coding methods which is able to provide coded data having a bit rate corresponding to the transmission rate of the transmission line, and a transmitting step of transmitting the coded data obtained with the coding method selected in the selecting step.
According to an eleventh aspect of the present invention, in a receiving apparatus for receiving coded data resulted from encoding a digital signal via a predetermined transmission line, the receiving apparatus comprises receiving means for receiving the coded data encoded by a coding method capable of providing data having a bit rate corresponding to a transmission rate of the transmission line, and decoding means for decoding the coded data.
According to a twelfth aspect of the present invention, in a receiving method for receiving coded data resulted from encoding a digital signal via a predetermined transmission line, the receiving method comprises a receiving step of receiving the coded data encoded by a coding method capable of providing data having a bit rate corresponding to a transmission rate of the transmission line, and a decoding step of decoding the coded data.
According to a thirteenth aspect of the present invention, in a providing medium for providing a computer program for rendering a computer to execute processing to receive coded data resulted from encoding a digital signal via a predetermined transmission line, the computer program includes a receiving step of receiving the coded data encoded by a coding method capable of providing data having a bit rate corresponding to a transmission rate of the transmission line, and a decoding step of decoding the coded data.